Quaternary ammonium compounds comprise an important subcategory of surfactants because they contain unique properties. A main distinction between quaternary ammonium compounds and other surfactants is their unique structure. Quaternary ammonium compounds consist mainly of two moieties, a hydrophobic group, e.g., long alkyl group, and a quaternary ammonium salt group. The unique positive charge of the ammonium plays a key role, i.e., electrostatic interactions, between the surfactant and surface.
Industrial water systems employ process water to serve many different purposes but may be prone to microbial contamination and fouling. Fouling or deposition of any organic or inorganic material can occur even in industrial water systems treated with the best water treatment programs currently available.
If these industrial water systems are not periodically cleaned, then they will become heavily fouled. Fouling has a negative impact on the industrial water system. For example, severe mineral scale (inorganic material) will buildup on the water contact surfaces and anywhere there is scale providing an ideal environment for microorganism growth.
Evaporative cooling water systems are particularly prone to fouling. This fouling occurs by a variety of mechanisms including deposition of air-borne, water-borne, or water-formed contaminants; water stagnation; process leaks; and other factors. If allowed to progress, the system can suffer from decreased operational efficiency, premature equipment failure, and increased health-related risks associated with microbial fouling.
Fouling can also occur due to microbiological contamination. Sources of microbial contamination in industrial water systems are numerous and may include, but are not limited to, air-borne contamination, water make-up, process leaks and improperly cleaned equipment. These microorganisms can establish microbial communities on any wetable or semi-wetable surface of the water system.
Exopolymeric substances secreted by microorganisms aid in the formation of biofilms as the microbial communities develop on surfaces. These biofilms are complex ecosystems that establish a means for concentrating nutrients and offer protection for growth, and biofilms can accelerate scale, corrosion, and other fouling processes. Not only do biofilms contribute to reduction of system efficiencies, but they also provide an excellent environment for microbial proliferation that can include Legionella bacteria. It is therefore important that biofilms and other fouling processes be reduced to the greatest extent possible to minimize the health-related risk associated with Legionella and other water-borne pathogens.
Corrosion inhibitors are often added into upstream oil and gas production fluids to protect carbon steel pipelines and infrastructure from corrosion. Quaternary ammonium compounds have been used for many years as part of corrosion inhibitor formulations but are most often are bis quaternary species or species quaternized with benzyl chloride, which is known to be very hazardous.
There is a continuing need for quaternary ammonium compounds that fill this niche of surfactants and corrosion inhibitors.